spiff Posted August 27, 2013 Author Share Posted August 27, 2013 Most of my driving will be done on regular roads(some twisting) and mountain roads, some highway cruising(around 100-130kph) and maybe a trackday event couple of times a year... So the 3.36 sounds tempting as I think the taller gearing will provide a more comfortable ride at cruising speeds from around 80 to 130 kph, and better fuel consumption... Anyway I have the two diffs so I could just try them both and see what I like the best, but I only have one LSD so I need to figure out what diff I should mount that one to, I am contemplating the thought of installing the 3.36 with the obx helical for regular use and getting a second hand 1,5 or 2 way lsd to put in the 3.9 for trackday events... Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 27, 2013 Share Posted August 27, 2013 100 to 130 KPH will be awesome with the 3.9. Engine right on boost threshold when you need it. The 3.36 with a late gearbox will turn 2000 rpms at 80 kph, maybe 2500 at 95-100, something like that. Around boost threshold for a stock turbo... but it's so doggy compared to a 3.7... and 3.9 might be a bit short, but you would be doing 3-4 shifts at those speeds. Quote Link to comment Share on other sites More sharing options...
spiff Posted September 9, 2013 Author Share Posted September 9, 2013 Well, seems i dont have a 3,9 after all in ny car, i have a 3,5... So, 3,36 or 3,5 is the question now. Quote Link to comment Share on other sites More sharing options...
rejracer Posted September 10, 2013 Share Posted September 10, 2013 It depends on what transmission you are using, and how much power your machine is making. If you are using the ZXT T5 it has a very wide spread and low first gear, so I would go with the 3.36. Here is a copy of a speed-RPM calculator, this will tell you basically what Tony was saying above, except this gives you every possible trans/diff combo. https://docs.google.com/spreadsheet/ccc?key=0Ato3KCDX86aedFBpTkI0X0o5R2pQaHlrQzgzbGVrQXc&authkey=CPTj89IN&authkey=CPTj89IN#gid=0 Quote Link to comment Share on other sites More sharing options...
spiff Posted September 19, 2013 Author Share Posted September 19, 2013 It depends on what transmission you are using, and how much power your machine is making. If you are using the ZXT T5 it has a very wide spread and low first gear, so I would go with the 3.36. Here is a copy of a speed-RPM calculator, this will tell you basically what Tony was saying above, except this gives you every possible trans/diff combo. https://docs.google.com/spreadsheet/ccc?key=0Ato3KCDX86aedFBpTkI0X0o5R2pQaHlrQzgzbGVrQXc&authkey=CPTj89IN&authkey=CPTj89IN#gid=0 Wow! That's a comprehensive spreadsheet! A keeper for sure I have installed the BW T5, I also ended up installing the 3.36 rear with the obx helical, haven't had the chance to drive it all that much but the little I have driven it definetely feels promising... It sits at around 18-1900 rpm's when cruising at 80-90kph now versus 3000 before with the 4-speed. Much more comfortable but I also found myself braking speedlimits in urban areas as the wider gearing means I'm now going way to fast if giving it some beans when upshifting to 3rd, need to be careful. It's also a blast going up the steep mountains, seems to pull forever The only other thing I'm gonna try is swap the 75W-90 gear oil for dexron 3 type to see if it makes a difference for the better as I feel shifting isn't as crisp and snappy... I read this and it seems dexron is the way to go: http://datsunzgarage.com/borg/ Quote Link to comment Share on other sites More sharing options...
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